X-Git-Url: https://www.chiark.greenend.org.uk/ucgi/~ian/git?p=subdirmk.git;a=blobdiff_plain;f=subdirmk%2Fregen.mk.in;h=7e9f0cf108c98f45e997973f2e3ba627279e74ab;hp=f7a72192aa8c31319ffd20ba5164da92e2faf071;hb=ffddf030906bbf75b80acaf03043c46d1bba7dc1;hpb=9d3365682de5aabe3003fa7af54cfec0d099905a

diff --git a/subdirmk/regen.mk.in b/subdirmk/regen.mk.in
index f7a7219..7e9f0cf 100644
--- a/subdirmk/regen.mk.in
+++ b/subdirmk/regen.mk.in
@@ -14,17 +14,31 @@ $(CONFIG_STATUS): $(top_srcdir)/$(CONFIGURE)
 
 MAKEFILES += subdirmk/regen.mk
 
-main.mk $(MAKEFILES): makefiles.phantom ;
-.INTERMEDIATE: makefiles.phantom
-makefiles.phantom: 						\
+main.mk $(MAKEFILES): .makefiles.stamp ;
+.makefiles.stamp: 						\
 		$(top_srcdir)/subdirmk/generate			\
 		$(CONFIG_STATUS)				\
 		$(top_srcdir)/Perdir.mk.in			\
 		$(foreach m,$(MAKEFILES),$(top_srcdir)/$(m).in)
-	./$(CONFIG_STATUS)
-
-realclean: clean
+# This filtering arranges that we can often run config.status to
+# generate only particular output files.  We look for *inputs* that
+# have changed.  If the only inputs that have changed are ones that we
+# know affect only one output (Subdir.mk.in and regen.mk.in), we pass
+# config.status the corresponding output file names.  Otherwise we
+# pass nothing and config.status does them all.  We need to mention
+# regen.mk.in twice because if $(top_srcdir) is `.', make elides the
+# directory part from $?.
+	./$(CONFIG_STATUS) $(if					\
+		$(filter-out Subdir.mk.in %/Subdir.mk.in	\
+			subdirmk/regen.mk.in			\
+			$(top_srcdir)/subdirmk/regen.mk.in	\
+			, $?),,					\
+		$(patsubst %.mk.in,%.mk,$(filter %.mk.in,$?)))
+	touch $@
+
+realclean:: clean
 	$(RM) config.status config.log
-	$(RM) main.mk $(MAKEFILES)
+	$(RM) main.mk subdirmk/regen.mk $(MAKEFILES)
+	$(RM) $(addsuffix Makefile,$(dir $(MAKEFILES)))
 
 -include $(ALL_DEPFILES)